Most species, including humans, typically explore a small pool of potential mates before making a choice. However, the Uca crenulata crab in California (USA) examines up to 106 candidates before proceeding to mate.
With this behavior, female Uca crenulata crabs have earned the title of the “most selective” animal species in the world.
“As far as I know, no other species observes a large number of potential mates like California crabs do,” said Catherine deRivera, the head of the research team.
“Most invertebrates, some mammals, amphibians, and reptiles mate with their neighbors or the first candidate they encounter, or at least the first one that performs the courtship ritual correctly,” she explained.
In contrast, California female crabs are not easily won over.
DeRivera and her colleagues observed a population of crabs on an open tidal flat at the Sweetwater River estuary in Chula Vista, California. Male crabs dig flat burrows and group near their homes, signaling to females with their large claws, akin to waving a hand and saying “come here.” When females hear the calls, they peek into the burrow, reflecting the size of the male.
Normally, a simple glance into the burrow is enough for her to choose to approach another waving male. Occasionally, a female will fully enter the burrow, but ultimately, she leaves it. The female performs this act over 100 times before accepting her final home—the burrow that seems best suited to her size.
Once she chooses her mate, either she or he will seal the entrance. Each burrow contains several chambers, enough to accommodate four females, allowing some males to attract a small “harem” in their home. Females stay in the burrow for 2 to 16 days, during which they mate and lay eggs. The mother crab departs before the larvae hatch, and the young crabs will find their way to the water during high tide nights.
DeRivera believes that females are so selective because a moderately sized burrow offers better warmth and heat retention. It also allows the larvae to exit more easily, reducing the risk of predation.
Tom Langen, an assistant professor of biology and psychology at Clarkson University, stated that this research demonstrates that creatures with small brains are not necessarily foolish.
T. An (according to Discovery)
